Bitopertin increases time in the sun for adults with EPP in Phase 2 trial

Treatment also significantly reduced PPIX, improved patients' quality of life

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Treatment with the oral therapy bitopertin substantially increased sunlight tolerance for adults with erythropoietic protoporphyria (EPP) in a Phase 2 clinical trial, according to data on all its adult participants.

The experimental treatment also significantly reduced levels of protoporphyrin IX (PPIX) and improved quality of life for most patients. EPP is caused by mutations that result in PPIX’s toxic buildup, leading to disease symptoms.

Disc Medicine, the company developing bitopertin, presented the findings at the 65th annual meeting of theAmerican Society of Hematology (ASH) in the presentation “Interim Analyses from the Beacon Trial: A Phase 2, Randomized, Open-Label Trial of Bitopertin in Erythropoietic Protoporphyria.”

The Phase 2 clinical trial, called BEACON (ACTRN12622000799752), is testing bitopertin in people with EPP or X-linked protoporphyria (XLP) at sites in Australia. The study initially included only adults, but was expanded to include adolescents as well, according to Disc.

“This has been a tremendous ASH meeting for Disc. … We are especially proud and excited to present the updated results from BEACON, which reflect a more robust open-label data set and clearly indicate that reducing PPIX with bitopertin has the potential to result in dramatic benefits for patients with EPP,” John Quisel, PhD, president and CEO of Disc, said in a company press release.

All participants are being treated with bitopertin at doses of 20 or 60 mg a day. Initial data from the first 15 adults, reported earlier this year, suggested the therapy reduced PPIX levels and improved sunlight tolerance.

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At ASH, scientists shared interim findings from all 22 adults in BEACON. Consistent with earlier data, the results indicated bitopertin significantly reduced PPIX levels — on average, by more than 40%.

Before entering the study, the participants reported they almost always had signs of a reaction even with brief sunlight exposure. With bitopertin, sunlight exposure didn’t cause any noteworthy symptoms in more than half (54%) the reported instances.

The average time between exposure to sunlight and the onset of a toxic reaction was more than three times longer on bitopertin than before the study. Before, only about one in three (33%) days were free from EPP symptoms, on average. So far, patients have been free of symptoms for 78% of days, on average.

Rates of problematic reactions to sunlight have decreased by 92% with the oral therapy. Over six months, the average amount of time spent in sunlight without pain was 222.6 hours, more than three times higher compared to external data from people with untreated EPP.

Almost all of the participants reported noteworthy gains in measures of quality of life, according to Disc.

“Importantly, this improvement was observed across every efficacy measure of the study, including our analysis of the precedented pivotal endpoint, cumulative time in light over [six] months, which we debuted at this meeting,” Quisel said.

Bitopertin has so far been tolerated well, with no serious side effects reported. The most common safety-related issues so far include dizziness, lightheadedness, headache, and nausea.

Disc is running another clinical trial called AURORA (NCT05308472) that’s testing bitopertin against a placebo in adults with EPP. Results are expected early next year.

“We look forward to next year as we advance our full portfolio and obtain the readouts from AURORA and other studies,” Quisel said.

Bitopertin was originally developed by Roche to treat schizophrenia. Disc acquired the rights to develop it for EPP in 2021. The therapy is thought to help regulate the synthesis of heme, which is disrupted in EPP and other types of porphyria, by decreasing the amount of glycine, a molecule needed to make heme, moving into blood cells.